Deep geothermal energy - the risk of non-discovery of the hydrothermal resource

Abstract

The non-discovery of the hydrothermal resource is the main investment risk for deep geothermal. The core question of this master thesis is how to depict the risk of nondiscovery at the investigated site at Baden in an investment decision calculation. Thus I have chosen Percentiles of flow of water and temperature of the hydrothermal resource to calculate expected distributions of installable capacities and respective distributions of generation costs. For P50 (120 l/s), P40 (62 l/s) and P20 (12 l/s) flow rate of water expected generation costs range from 5-15 € / MWhth for P50 (120 l/s = 50% probability), 8-29 € / MWhth for P40 (62 l/s = 60% probability) and 44-131 € / MWhth for P20 (12 l/s = 80% probability). Distributions of generation costs are calculated with Percentiles P10-P90 for temperature gradient and with net present value method. Limit of the method of approach and derived conclusions is the question whether the Geological Model correctly reflects expected depth, flow rate and temperature of the hydrothermal resource. Since the Geological Model derived from GeoHeat.at is best available data, it is assumed for this work that indicated depth of rock layers and Percentiles for temperature and flow rate of the hydrothermal resource are correct. Prospective market sales price is assumed with 36 € / MWhth and thus the site of Baden may be profitable for geothermal heat production. In order to depict the riskof non-discovery in an investment decision calculation it can be either used a higherdiscount rate (reflecting the risk of non-discovery) or if a risk insurance against nondiscovery is possible, this is shown in investment costs (premium for risk insurance). To solve the risk of non-discovery from an economic point of view the investment risk needs to be spread across a given portfolio as it is done in the oil and gas industry (Portfolio Approach) which would make it possible to insure individual geothermal drilling project against the risk of non-discovery. Given the geological risk whether the hydrothermal resource is found in sufficient quantity (l/s) and quality (°C) the establishment of an international or European Geothermal Risk Insurance Fund (EGRIF) may be able to solve the investment risk of non-discovery. This can facilitate market deployment of deep geothermal energy especially in low and medium enthalpy areas.